{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "$id": "http://schema.ruter.no/externaldisplay.json",
  "type": "object",
  "title": "External Display MQTT Message",
  "description": "Notification that the external displays should show new destination information",
  "required": [
    "eventTimestamp",
    "destination"
  ],
  "additionalProperties": false,
  "properties": {
    "eventTimestamp": {
      "$id": "#/properties/eventTimestamp",
      "type": "string",
      "description": "Event timestamp must be ISO 8601 UTC",
      "format": "date-time"
    },
    "publicCode": {
      "$id": "#/properties/publicCode",
      "type": "string",
      "description": "Publically-known number of the line"
    },
    "destination": {
      "$id": "#/properties/destination",
      "type": "string",
      "description": "Destination of the bus"
    },
    "alternativeMessage": {
      "$id": "#/properties/alternativeMessage",
      "type": "string",
      "description": "Alternative message to be displayed on second line of display"
    }
  }
}